Energy absorbing steering column

ABSTRACT

Collapsible steering column for an automotive vehicle including a polygonal shaped jacket having a plurality of rows of elongated slots therein, and a movable die member attached to the vehicle floorboard for folding the jacket walls back upon themselves upon impact.

United States Pate [1 1 Smith Nov. 4, 1975 Program on January 28, 1975 as document no. B 360,296.

52 U.S.C1. 74/492; 188/1 c 51 Int. (11. B62D 1/18 58 Field of Search 74/492, 493; 188/1 c [56] References Cited UNITED STATES PATENTS 3,143,321 8/1964 McGehee et a1 188/1 C X 3,236,333 2/1966 Mitchell 188/1 C 3,339,674 9/1967 Kroell et a1. l 188/1 C 3,528,530 9/1970 Franck et a1 188/1 C 3,538,785 11/1970 Grancon 74/492 3,608,677 9/1971 Wykes 188/1 C 3,717,046 2/1973 Takao et al 74/492 3,747,427 7/1973 Milton 74/492 3,760,650 9/1973 Pardy.. 74/492 3,779,591 12/1973 Rands 188/1 C Primary ExaminerAllan D. Herrmann Attorney, Agent, or Firm-Talburtt & Baldwin [57] ABSTRACT Collapsible steering column for an automotive vehicle including a polygonal shaped jacket having a plurality of rows of elongated slots therein, and a movable die member attached to the vehicle floorboard for folding the jacket walls back upon themselves upon impact.

4 Claims, 6 Drawing Figures US. Patent Nov. 4, 1975 Sheet 1 of2 3,916,720

us. Patent Nov.41975 sheetzofz 3,916,720

Xvi k5 ENERGY ABSORBING STEERING COLUMN BACKGROUND OF THE INVENTION This invention relates to steering column assemblies, and more particularly to a movable die for an energy absorbing collapsible steering column assembly for automotive vehicles. This application is related to the structure shown in copending U. S. application Ser. No. 360,294, filed May 14, 1973.

Collapsible energy absorbing steering columns of various types have been known for many years and have taken various forms. For example, many early types of columns utilized telescoping members having hydraulic fluid therein which passed through one or more parts as the members telescoped. Another type developed recently included a column jacket having circumferentially arranged diamond-shaped openings forming a mesh which collapsed under a predetermined load. Another type recently developed includes a pair of telescoping jacket members having balls between the walls thereof, the balls having an interference fit with the walls and causing deformation of one or both members when subjected to a predetermined load. Still another type is described in U. S. Pat. No. 3,339,674. This type utilizes a tubular member which is telescoped axially upon itself to progressively radially bend the walls and then reverse such walls axially of the tube. The present invention is generally of the latter type, although it is different in construction as well as improved.

BRIEF SUMMARY OF THE INVENTION Briefly, this invention comprises a steering column having a movable die member for deforminga jacket portion of the steering column.

One of the primary objects of this invention is to provide an energy absorbing steering column for an automotive vehicle having a movable die.

Another object of this invention is to provide a collapsible steering column of the type described which provides a controlled resistance to collapse for absorbing energy.

Another object of this invention is to provide a die for a collapsible steering column such as described, which will cause the column to collapse in a predetermined manner upon impact of a predetermined magnitude.

Still another object of this invention is to provide a collapsible steering column of the type described which includes a movable die adapted to seat itself in the appropriate position to effect reverse bending of the walls of the column, regardless of the angular relationship between the floorboard and the column, this increasing the versatility of application of the column.

Still another object of this invention is to provide a die for a collapsible steering column of the class described which is economical in construction and effective in operation.

Other objects and advantages of this invention will be made apparent as the description progresses.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings in which one of various possible embodiments of this invention is illustrated,

FIG. 1 is a fragmentary pictorial view of a steering column utilizing a die constructed in accordance with this invention;

FIG. 2 is an enlarged fragmentary side elevation of the column shown in FIG. 1;

FIG. 3 is a longitudinal section of the column shown in FIG. 2;

FIG. 4 is an enlarged fragmentary view of FIG. 3 during an initial phase of the reverse bending of the column jacket;

FIG. 5 is an enlarged fragmentary elevation of a column jacket, longitudinally cut down the middle, after the column has been collapsed; and

FIG. 6 is a view of FIG. 5 taken from the other side of the column.

Like parts are indicated by corresponding reference characters throughout the several views of the drawmgs.

DESCRIPTION'OF THE PREFERRED EMBODIMENT Referring to the drawings, a steering assembly having a die constructed in accordance with this invention is shown generally in FIG. 1 at 1. Assembly 1 includes a steering wheel 3 mounted at the upper end ofa steering column 5. Column 5 extends downward past an instrument panel 7 and through a cowl or firewall 9 to a steering sector 11.

Column 5 includes a jacket 13 which extends from a steering wheel hub 15 to the firewall 9 and is connected to the instrument panel 7 by releasable clamping brackets 17. A multipiece shift tube 19 extends from the hub 15 downwardly through the jacket to a shift lever 21 located below the firewall 9. A multi-piece steering shaft 23 is cdnnected at its upper end to the steering wheel 3 extends downwardly through the shift tube 19 to the steering sector 11. The shift tube 19 and shaft 23 may be of the genera! type shown in U. S. Pat. 'No. 3,373,629 and are adapted to telescope upon themselves under a predetermined load.

Jacket 13 is formed of a sheet metal blank rolled into a column having a relatively stiff or rigid upper portion 25 and an energy absorbing portion 27. The upper portion 25 is generally circular, but the lower energy absorbing portion 27 is generally polygonal in shape. More specifically, the energy absorbing portion 27 has a plurality of longitudinally extending rows 29 of longitudinally extending slots 31 spaced around the perimeter of the jacket. The slos 31 of each row have radiused ends 33 to reduce the incidence of stress risers and are separated from one another by webs 35. The long side walls 37 formed between the rows 29 of slots 31 are generally flat and are approximately the same width as the slots. The slots of each row are offset in a longitudinal or axial direction by a distance equal to approximately one-half the length of the slots. The lower end of the column jacket is formed so that, with the exception of the end slot in five of the rows, the end slots of alternative rows are open and the slots themselves extend up the jacket approximately one-half of the normal length of the slots. The five end slots referred to above are shorter than the remaining end slots to provide enlarged webs 39.

The lower end of the jacket 13 is connected by a plurality of rivets 41 to the upper end of a stamped mandrel or die 43. The mandrel is tubular in shape and extends through an opening 45 in firewall 9, being resiliently held there by a resilient ring-shaped mounting bushing 47. Bushing 47 has a radially extending flange portion 49 extending from a tubular portion 51 on the upper or rearward side of the firewall 9. A bead 53 is formed on the forward end of the bushing on the lower side of the firewall.

The rearward end of the mandrel 43 extends into the lower portion of the jacket 13, and as mentioned previously, is attached thereto by the rivets 41. A die portion 55 is formed by folding the mandrel upon itself and provides a 90 arc or curved portion 57.

The curved portion is tangent at its rearward end to the forward end of the tubular portion of the mandrel and curves outwardly therefrom. The forward tubular portion 59 of the mandrel extends through the bushing 47 and is resiliently supported on the shift tube 19 by an annular seal 61 and an annular bushing 63. The lower end of the shaft 23 is held in a centered relationship with the shift tube 19 by a bearing 64 biased upwardly by a spring 65. Spring 65 reacts againsta clamping ring 67 or other convenient reaction member attached to the shaft.

The curved portion 57 of the mandrel 43 is spaced rearwardly from the firewall 9 a short distance. Thus, the mandrel will move forwardly this distance before the curved portion 57 seats on the bushing 47 and floorboard or firewall 9. This freedom of movement allows for much greater tolerances of the connection between the column and the firewall and compensates for any minor variations in the angle of the column with the firewall between varous vehicles. For example, in two identical vehicles the angularity of the column with respect to the firewall may vary slightly as a result of various manufacturing tolerances. The resilient bushing 47 and movable mandrel 43 allow for such variations.

Assuming the various components of the steering column are in the position shown in FIGS. 1, 2 and 3, operation of the column is as follows:

If a force of sufficient magnitude is applied to the steering wheel by the driver, for example, the clamps 17 will be released and the column will move downwardly due to the axial component of the force. First, the rivets 41 will hold the mandrel 43 and jacket 13 together, causing the mandrel to move downwardly and forwardly. When the curved die portion 55 engages the bushing 49 and firewall 9, the die portion will stop. If the force on the column is of sufficient magnitude, the shanks of the rivets will shear and the forward end of the column jacket 13 slide toward die portion 55.

Referring now to FIG. 4, as the forward end of the jacket 13 initially engages the die section 55 the jacket walls begin to curl outwardly and then rearwardly upon themselves until the original forward end of the jacket is folded back over 360 and in fact, may approach the 540 curl shown in FIGS. and 6.

As the jacket passes over the die portion 55 and is flared outwardly thereby the slots 31 open up into generally diamond shapes as the walls 37 and webs 35 and 39 bend to allow for the increased perimeter of the jacket. The peripheral continuity of the jacket is altered by the spreading slots as the jacket is flared outwardly by the die.

As the jacket continues to move forwardly the curled end portion moves back along the jacket without further curling. The only additional curling takes place as the walls of the jacket are reversely curled approximately 180 by the die portion 55. In addition, work or energy absorption is obtained by uncurling or straightening the curl as the expanded jacket begins to move back up on the outside of the jacket. The jacket assumes the condition shown in FIGS. 5 and 6 after a predetermined impact has occurred. Energy is absorbed by the reverse bending and curling created by the die portion and the uncurling created by the hoop strength of the expanded jacket.

Until the expanded jacket reaches the position shown in FIG. 4 the resistance to collapse increases to a predetermined level. As further collapse occurs and the jacket goes from the FIG. 4 position to the FIGS. 5 and 6 position, the resistance to collapse generally levels off and remains generally constant. This provides maximum efficiency at a desired rate.

The column is relatively rigid and has a relatively high bending resistance since the slots 31 extend longitudinally of the jacket prior to impact. This substantially reduces the possibility of collapse by bending when the driver is thrown against the steering wheel. However, the slots 31 reduce the hoop strength of the jacket and permit the jacket to be flared outwardly by the die portion 55.

In view of the foregoing it will be seen that the several objects and other advantages of this invention are achieved.

Although only one embodiment of the invention has been disclosed and described, it is apparent that other embodiments and modifications of the invention are possible.

I claim:

1. A die device for a tubular energy absorbing steering column jacket comprising a movable die means connected to a floorboard of a vehicle and movable with respect thereto, said die means moving toward said floorboard when a force of a predetermined magnitude is applied to the upper end thereof, said die means comprising a tubular member having a forward tubular portion and a rearward tubular portion, and a curved die portion between said tubular portions, said die portion being formed by the wall of said tubular member being folded upon itself.

2. A die device as set forth in claim 1 wherein said die portion is spaced rearwardly of said floorboard, and a resilient bushing located between said forward tubular portion and said floorboard in said opening.

3. A die device as set forth in claim 2 wherein said resilient bushing is annular and has a tubular portion, a radially extending flange on one end of said tubular portion and a bead on the other end of said tubular portion.

4. A die device for an energy absorbing steering column adapted to extend through an opening in a wall,

formed by folding the wall thereof upon itself. 

1. A die device for a tubular energy absorbing steering column jacket comprising a movable die means connected to a floorboard of a vehicle and movable with respect thereto, said die means moving toward said floorboard when a force of a predetermined magnitude is applied to the upper end thereof, said die means comprising a tubular member having a forward tubular portion and a rearward tubular portion, and a curved die portion between said tubular portions, said die portion being formed by the wall of said tubular member being folded upon itself.
 2. A die device as set forth in claim 1 wherein said die portion is spaced rearwardly of said floorboard, and a resilient bushing located between said forward tubular portion and said floorboard in said opening.
 3. A die device as set forth in claim 2 wherein said resilient bushing is annular and has a tubular portion, a radially extending flange on one end of said tubular portion and a bead on the other end of said tubular portion.
 4. A die device for an energy absorbing steering column adapted to extend through an opening in a wall, comprising a tubular die member located at the lower end of said column, means mounting said die member for limited movement relative to said wall, said die member having a portion thereof curved outwardly for deforming said column outwardly as the latter is forced thereover, said portion of said die member being formed by folding the wall thereof upon itself. 